Lithuanian startup launches open-source network to detect Shahed-type drones

ggiuliomagnifico about 3 hours ago 41 commentsRead Article on lrt.lt

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tristanj•about 2 hours ago

Shahed drones have increased in altitude from ~500m at the beginning of the Ukraine war to 2000-3000m, which is a 4x reduction in noise on the ground. The higher the drones are, the less noise they make at ground level, and the less effective this ground-based microphone system will be. The drones have moved to elevations to make them more difficult to target with ground based weapons. Reductions in ground noise are a secondary effect.

The latest versions of Shahed can reach 5000m in altitude, which would largely be inaudible on the ground.

dghlsakjg•16 minutes ago

At those higher altitudes they are trivial for radar to detect, and from farther away too. They are adapting cheap commodity used marine radars to get this done in some places

I suspect the Shaheds are going higher to mitigate AA ground fire. Higher up you have to send a missile or interceptor up.

It’s a trade off.

anovikov•about 2 hours ago

It's not about "can reach", it's fairly easy to get them to fly even higher. It's about danger of interceptors vs danger of detection. Today's Ukrainian detection network (based on radars) is so dense there is no way to hide from it anywhere, anyway, so high altitude wins.

Hackbraten•26 minutes ago

> It's about danger of interceptors vs danger of detection.

What's with that "vs" trade-off?

You're saying avoiding detection requires high altitudes.

What do interceptors have to do with that?

anovikov•17 minutes ago

Interceptors are battery powered and their energy budget and thus range suffers if they have to climb high.

Detection is facilitated by radar, low altitude means flying under the radar (due to curvature of the Earth) - except radar network is now so dense, it in practice can't work anymore. So they can fly low or high they will be detected anyway - but flying high reduces interceptor's reach and makes intercept geometry harder, giving them better chances to slip through.

warumdarum•about 2 hours ago

So film the sky during charging and run a llm on it?

Neywiny•about 1 hour ago

Or an image detection model. Fraction of the compute and can run even on edge embedded. And easy to train with your own data

MiracleRabbit•about 2 hours ago

If these Shahed drones have a propeller they should have a brutal signature between 0-250Hz as they are moving a lot of air. And if the engine speed of the Shahed stays constant it will be even easier to detect it ("Angry lawnmower sound".. but that's only the high frequency part of it).

There are extremely sensitive differential pressure sensors (like SDP600-25Pa) available from Sensirion that aren't overly expensive.

Use one differential side and connect it to a kitchen funnel for directional listening the other one to a plastic bottle with a tiny hole in it. This way the sensor will "Null" out the environmental pressure (which the bottle follows very very slowly) from both inputs. It then only will pick up everything high frequency which is left over (and the bottle cannot follow because of its small hole).

This way I was able to detect washing machines that have a physical link to a house from many hundred meters (machine spinning -> house wall shaking -> pressure waves) away. The speed pattern of washing machines when spinning is very unique (several steps over many seconds).

Add this with some GPS PPS frame timestamping and you should have a nice tracking network that doesn't require a lot of bandwidth. But maybe the setup must switch to analog differential pressure sensors as these Senirion-I2C sensors do not have a Sync ping for super precise timestamping.

customguy•about 1 hour ago

> Use one differential side and connect it to a kitchen funnel for directional listening the other one to a plastic bottle with a very very small hole in it. It will pick up everything high frequency that's different to the environmental pressure.

Nevermind drones, and war, that's all fine; but I need to know more about this. Is there a phrase or name for this I could use to find more information, maybe example schematics?

MiracleRabbit•39 minutes ago

The Sensirion SDP600-25Pa speaks I2C and only has a handful of primitive commands. Add this and 3.3V and you are done.

I'm 99.5% sure if you throw Claude with a datasheet on it will Slop out working code for a ESP32 with ESP-IDF.

Hnrobert42•about 1 hour ago

Interesting! There are a lot of super loud cars in my urban area. I want to catalog where and when they drive, so I can stand on the side of the street and shake my cane at them.

brookst•12 minutes ago

I’ve always dreamt of building a mesh network of loud vehicle detectors that would map current loud noises and track where loud vehicles live, coupled with very powerful parametric speakers. So when e.g. the network detects a loud motorcycle at 3am anywhere in town, that live sound is instantly played at high volumes targeting only homes where other loud vehicles live.

Somehow there has been little VC interest in this idea.

warumdarum•11 minutes ago

https://freesound.org/people/PicassoCT/sounds/850225/

Curmudgeon Ai?

amluto•19 minutes ago

What’s the frequency response of that sensor? The datasheet says nothing.

MiracleRabbit•17 minutes ago

Honestly: don't know.

My experiments never had a dependency on linearity.

ShinyLeftPad•23 minutes ago

Doesn't wind fool this?

MiracleRabbit•19 minutes ago

Theoretically wind can be Nulled with a 4-way water splitter that are placed in 90° angles (+ a connector at the bottom to the sensor). As long they are orthogonal the wind pressure coming from one side will cause a counter-pressure on the opposite.

Only pressure waves coming into all holes at the same time will reach sensor.

Never tested it. Only a Gedankenexperiment as Einstein would say.

ejanus•about 1 hour ago

Interesting! I will like to see your circuits, if any.

MiracleRabbit•41 minutes ago

Not much circuits needed.

The SDP600-25Pa speaks I2C and only has a handful of commands.

Just read it out with a microcontroller you love (like ESP32) and send the samples to a host for analysis. The ESP32 has limited I2C time stretching capabilities limiting it in the highest resolution modes of the sensor - but often that's not a big factor.

To not overwhelm the poor processor and Wifi maybe better a bunch of frames (like 512 or more).

stavros•about 1 hour ago

Isn't detecting pressure waves in air exactly what microphones do?

MiracleRabbit•about 1 hour ago

Yes. But they usually are not performing very good between 1-250Hz.

Sensirion is using a thermal flow-sensing principle method which is basically a heated plate that cools/heats up when air passes it - making it extremely sensitive in this range.

tpolm•about 2 hours ago

I wonder how this system can be protected from spam - if anyone can send data there, enemy can, too

embedding-shape•about 2 hours ago

I feel like if/once they reach the number of expected participants (10k), it'd be easy to filter out the spam as long as the majority are truthful.

tristanj•about 3 hours ago

SpaceX received a $4 billion military contract to do this, but with radar and from orbit.

Aboutplants•25 minutes ago

Multi billion dollar spend to “see” $2,000 aircraft and try to shoot it down with multi million dollar equipment. The speed to produce and cost effectiveness of these drones are seemingly at a massive advantage right now vs Defense capabilities and straight up cost and looks to be that way for a good while.

Avicebron•about 2 hours ago

As much as I like to point and guffaw at "bad evil rocket man" the from orbit bit is doing a massive amount of lift (pun not intended) for that price.

nefarious_ends•about 1 hour ago

How is Elon evil?

brookst•10 minutes ago

DOGE literally killed people.

https://www.currentaffairs.org/news/how-elon-musk-killed-hun...

snovv_crash•about 1 hour ago

You missed the part where he did a Sieg Heil during Trump's inauguration?

reboot81•about 2 hours ago

Wouldn’t a purpose built Esp32 with microphones aimed at the sky do a better job? It would be always on, better directional targeting.

rdtsc•about 2 hours ago

I believe Ukrainians had already deployed such a system. This is specifically designed to use old Android phones already sitting in a drawer somewhere without any other use, and most importantly by anyone without technical skills.

AIcanbiteme•about 1 hour ago

Baltics are very involved in the war in Ukraine, for instance, Slovenia started NAFO.

nxpnsv•about 1 hour ago

Slovenia is not baltic